Alright, let's work through 51616481 times 12940963 step by step
51616481 × 12940963 = 12940963 × (51616481)
+ 12940963 × 1 that results in 12940963
+ 12940963 × 80 that results in 1035277040
+ 12940963 × 400 producing 5176385200
+ 12940963 × 6000 that results in 77645778000
+ 12940963 × 10000 which equals 129409630000
+ 12940963 × 600000 that is equal 7764577800000
+ 12940963 × 1000000 that is equal 12940963000000
+ 12940963 × 50000000 giving us 647048150000000

= 667966970811203
